Electric clock



Sept. 26, 1933. P, MacGAl-IAN 1,927,895

ELECTRIC CLOCK Filed Aug. 8, 1930 i Fig. 2 Z

i 9 g g-3131 3" 2 /4 g 35 7 40 6O /0 a I 5 INVENTOR Paul MacGahan.

' ATTORNEY Patented Sept. 26, 1933 ELECTRIC CLOCK Paul MacGahan, Orange,N. J., assignor to Westinghouse Electric & Manufacturing Company, acorporation of Pennsylvania Application August 8, 1930. Serial No.473,847

4 Claims.

This invention relates broadly to a timing device driven by asynchronous motor, and has particular relation to a motor-driven clockmechanism in which an indicator is provided '5 whereby notice is givenin the event of a tem porary failure of current to the motor.

In apparatus of the above described character, it is necessary, in theevent of failure of current supplying the motor, that some means beprovided to call attention to the fact that the clock has been stopped.This is especially important when, as is often the case, the currentfailure lasts for a relatively short space of time. Upon resumption ofcurrent, the clock will immediately start, and, if there is noindication that a stoppage has occurred, it will not be apparent thatthe clock reading is inaccurate.

The former practice for accomplishing the above-mentioned object was toprovide an auxiliary indicatoror signal, on the dial of the clock,actuated by an independent mechanism. My invention utilizes a part ofthe necessary clock mechanism, namely, the second hand or pointer, as astoppage indicator.

. An object of my invention is to provide a mechanism of; theabove-mentioned character in which one of a plurality oftime-indicatingmembers of a clock is utilized to indicate a failure of current to theclock motor.

Another-object of my invention is to provide means whereby movement ofone of a plurality of normally moving indicating members is permanentlyarrested upon failure of current to the clock motor and means wherebymovement of the a member may be re-established, upon reception ofcurrent flow through the motor, at the will of an operator.

These and other objects of my invention are more fully explained in thefollowing description, taken in conjunction with the accompanyingdrawing, in which p c Figure 1 is a schematic View of a clock mechanismconstructed in accordance with my invention, and i Fig. 2'is aschematic'view of a modification of the mechanism shown in Fig. 1.

Referring to Fig. 1, a source of current is indicated as comprisingconductors 1 and 2. A synchronous motor 4,. provided with the usual polepieces 5,, field winding 6 and a rotating armature'7, is connected tothe conductors 1 and 2 through a flexible cable 3. A plurality ofindicators or pointers 8, 9 and 10 cooperate with the numerals 11,arranged in an ordinary manner around the circumference of a clock dial12.

The pointers 8, 9 and 10 are secured, respectively, to one end of aplurality of concentrically disposed actuating shafts 13, 14 and 15. Theshafts 13 and 14 are connected, respectively, through the gear train 16,to the shaft 35 of the motor armature 7. The shaft 15 of the second hand10 is connected, through a Worm gear 17 and worm 18, a pair of clutchmembers 19 and 20, shaft 21, gear wheel 22 and pinion 23, to the shaft35 of the motor armature '7. The clutch 65 member 20 is splined or keyedto the shaft 21 in such manner that the clutch member 20 may movelongitudinally with respect to the shaft 21.

A bell-crank lever 24 having, at one extremity, a shifting fork or yoke25, adapted to cooperate with the collar of the clutch member 20, isprovided, at its other extremity, with an armature 26. The bell-cranklever is journalled to a shaft or pin member 28. A spring member 29 isprovided to normally bias the bell-crank lever 24 to the position shownin the drawing. Stop members 30 and 41 are provided to limit the arc oftravel of the bell-crank lever 24.

A manually operable reset member 31, substantially of U-shape, isjournalled on the shaft 33. A bearing member 32, at one end of theresetmember, is adapted to cooperate with the bell-crank lever 24 for apurpose to be hereinafter more fully explained. The other end of thereset member 31 is provided with a push button 36.

The operation of my mechanism is as follows:

To start the clock, the synchronous motor 4 is connected to theconductors land 2, whereupon current will flow through the coil 6, andthe armature '7 will rotate the indicators or pointers 8 and 9 throughthe gear train 16. At the same moment, the operator will pressdownwardly upon the push button 36, thereby moving the bell-crank lever24 in such manner that the armature 26 will be placed in close proximityto the pole pieces 5 of the motor 4 and will be under the influence ofthe leakage flux of the pole pieces. The clutch member 20, at the sametime, will move longitudinally, along the shaft 21, into engagement withthe clutch member 19. The second hand 10, therefore, will also beconnected to the shaft of the motor armature 7.

In the event of any failure of current in the conductors 1 and 2, thefield winding 6 and the pole pieces 5 of the motor 4 will bedeenergized. The armature 26 of the bell-crank lever 24, under theinfluence of the spring 29, will be moved away from the pole pieces 5.At the same time, the clutch member 20 will be disengagedfrom thecooperating clutch member 19, and the connection between the shaft 15 ofthe second hand 10 and the shaft 35 of the motor armature 7 will bebroken.

If, however, current flow is reestablished in the conductors 1 and 2,the synchronous motor 4 will immediately start, the indicators orpointers 8 and 9 will thus resume their travel around the clock dial 12,but the second hand 10 will remain motionless.

The reading of the indicators or pointers 8 and 9 will thus beinaccurate, since the time interval of the duration of currentinterruption has not been recorded. An observer, by glancing at theclock and finding the second hand 10 motionless, is notified that thecurrent has been interrupted. He immediately places the pointers 8 and 9in their correct positions and then presses on the push button 36, whichaction, as explained above, will reestablish travel of, the second hand10.

Referring to the modification shown in Fig. 2, a second hand or pointer10 is secured to one end of a shaft 15. The other end of the shaft 15 isrotatably mounted in one end of a lever 37. The lever 37 is journalledto a pin 38. Armature 26 is secured, by means of a pin 27, to the lever37. A worm gear 1'7, adapted to cooperate with the worm 18, is fixedlysecured to the shaft 15. A slot 39 is provided in the second-hand dial40 to allow lateral movement of the shaft 15 and the second hand orpointer 10, for a purpose to be hereinafter explained.

The operation of the mechanism shown in Fig. 2 is as follows:

When it is desired to start the clock, the indicating members 8, 9 and10 are placed in their respective positions. The motor 4 is thenconnected to conductors 1 and'2 through the cable 3. At the same moment,push button 32 is pressed downwardly by the operator. The reset member31 thus moves the lever 3'7 and shaft 15 upwardly until movement of thelever 3'7 is arrested by the stop member 41. The armature member 26 isthus placed under the influence of the leakage fiux of pole pieces 5 ofthe motor 4. The worm gear 17 will engage the worm 18, and the shaft 15and the second hand 10 will move upwardly in the slot 39 to occupy aposition in the center of the second-hand dial 40. The armature 7 willthen rotate the indicators or pointers 8, 9 and 10 through the geartrain 16 and shafts 13, 14 and 15.

In the event of any failure of current in the conductors 1 and 2, thepole pieces 5-of the motor 4 will become deenergized, and the armature26, lever 3'7 and shaft 15 will drop downwardly under the influence ofgravity until further downward movement is arrested by the stop member30.

If current is reestablished in the conductors 1 and 2, the motor 4 willimmediately start, and actuation of the indicating members 8 and 9 willbe immediately reestablished. Actuation of the indicating member 10 willnot be reestablished because the worm gear 17 has been disengaged fromworm 18.

The reading of the indicators 8 and 9 will be inaccurate because thetime interval of the duration of current interruption has not beenrecorded. The observer is notified of this fact when he notices that theindicator 10 remains stationary. He will then immediately place theindicators 8 and 9 in their proper positions and restart the indicator10, as explained above.

I do not wish to be restricted to the specific arrangements of parts asdescribed and illustrated, as it is apparent that various modificationsthereof will fall within the spirit and scope of my invention. I desire,therefore, that only such restrictions be imposed as are indicated inthe appended claims.

I claim as my invention:

1. Time mechanism comprising a plurality of timed driven members, acommon driving source therefor comprising an alternating-current motorcapable of operating in synchronism with a source of timed electricalalternations, the mechanism being of a type in which said motor and saiddriven members will stop upon a substantial cessation of thealternating-current power-supply for said motor, characterized byelectro-responsive means for automatically causing said motor to startupon an establishment of said power-supply, means for simultaneouslyautomatically starting less than all of said driven members andoperating the same in synchronism with said motor while causing theremainder of said driven members to remain still, separately controlledmeans for placing said remainder of the driven members in synchronousdriven connection with said motor after a period of interruption of thepower-supply, and electromagnetic means responsive to the substantialmaintenance of said power-supply for thereafter maintaining saidoperation of said remainder of the driven members as long as thepower-supply is substantially maintained.

2. Clock mechanism comprising a plurality of time-indicating, drivenmembers adapted to operate at different speeds to indicate differentsubdivisions of time, one of said driven members being aseconds-indicating member, a common driving source therefor comprisingan alternatingcurrent motor capable of operating in synchronism with asource of timed electrical alternations, the mechanism being of a typein which said motor and said driven members will stop upon a substantialcessation of the alternatingcurrent power-supply for said motor,characterized by electro-responsive means for automatically causing saidmotor to start upon an establishment of said power-supply, means forsimultaneously automatically starting all of said driven its iio

members except said seconds-indicating member and operating the same insynchronism with said motor while causing the seconds-indicating memberto remain still, separately controlled means for placing saidseconds-indicating member in synchronous driven connection with saidmotor after a period of interruption of the power-supply, andelectromagnetic means responsive to the substantial maintenance of saidpower-supply for thereafter maintaining said operation of saidseconds-indicating member as long as the powersupply is substantiallymaintained.

3. Time mechanism comprising a plurality of timed driven members, acommon driving source therefor comprising an altemating-current motorcapable of operating in synchronism with a source of timed electricalalternations, the mechanism being of a type in which said motor and saiddriven members will stop upon a substantial cessation of thealternating-current powersupply for said motor, characterized byelectroresponsive means for automatically causing said motor to startupon an establishment of said power-supply, means for simultaneouslyautomatically starting less than all of said driven members andoperating the same in synchronism with said motor while causing theremainder of said driven members to remain still, separately controlledmeans for placing said remainder of the driven members in synchronousdriven connection with said motor after a period of interruption of thepower-supply, and electromagnetic means responsive to theelectromagnetic flux produced in said motor for thereafter maintainingsaid operation of said remainder of the driven members as long as thepower-supply is substantially maintained.

4. Clock mechanism comprising a plurality of time-indicating, drivenmembers adapted to operate at different speeds to indicate differentsubdivisions of time, one of said driven members being aseconds-indicating member, a common driving source therefor comprisingan alternating-current motor capable of operating in synchronism with asource of timed electrical alternations, the mechanism being of a typein which said motor and said driven members will stop upon a substantialcessation of the alternatingcurrent power-supply for said motor,characterized by electro-responsive means for automatically causing saidmotor to start upon an establishment of said power-supply, means forsimultaneously automatically starting all of said driven members exceptsaid seconds-indicating member and operating the same in synchronismwith said motor while causing the seconds-indicating member to remainstill, separately controlled means for placing said seconds-indicatingmember in synchronous driven connection with said motor after a periodof interruption of the power-supply, and electromagnetic meansresponsive to the electromagnetic flux produced in said motor forthereafter maintaining said operation of said seconds-indicating memberas long as the powersupply is substantially maintained.

PAUL MACGAHAN.

